Casing hanger



CASING HANGER l Filed July 19, 1967 Sheet of 2 l2 FIG'Z 0000009 T i 26 JLL FIG. I INVENTORS:

G. 0. JOHNSON F. E. GIBBS THEIR AGENT v July 8, 1969 e. D. JOHNIISON ET AL 3,454,088

CASING HANGER Sheet 2 of 2 Filed July 19, 1967 INVENTORSI- G. D. JOHNSON F. E. GIBBS BY: (+1

FIG. 5

THEIR AGENT United States Patent 3,454,088 CASING HANGER Glenn D. Johnson, Downey, Calif., and Fred E. Gibbs, Houston, Tex., assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed July 19, 1967, Ser. No. 654,406 Int. Cl. E21b 23/00, 33/035 US. Cl. 166124 9 Claims ABSTRACT OF THE DISCLOSURE A retrievable casing hanger is provided which seats and seals a casing string within a well casing head. By rotating a running pipe string attached tool, slips are set to secure the casing string axially within the well bore and a radially expansible packer is compressed against the casing head wall. Simultaneously, a mandrel-driven nut which supports the casing string on the running pipe string is retracted to release the casing string from surface support.

This invention relates to apparatus for use on oil and gas well installations and pertains more particularly to apparatus for suspending a string of well casing or tubing within a well from a casing head. The present invention is especially concerned with a casing suspension system for use in underwater wellhead installations.

In an attempt to locate new oil fields, an increasing amount of well drilling has been conducted at offshore locations, such, for example, as off the coast of Louisiana, Texas and California. As a general rule, the strings of casing in a well, together with the tubing string or strings, extend to a point well above the surface of the water Where they are closed in a conventional manner that is used on land wells, with a conventional wellhead assembly being attached to the top of the casing. Attempts have been made recently to provide methods and apparatus for drilling and completing a well wherein both the well casing head and subsequently the wellhead assembly and casing head closure device are located underwater at a depth sufficient to allow ships to pass over them. Preferably, the casing head and wellhead closure assemblies are located close to the ocean floor. In order to install equipment of this type underwater in depths greater than the shallow depths at which the diver can easily operate, it has been necessary to design entirely new equipment for this purpose.

It is, therefore, an object of this invention to provide a casing hanger adapted to be secured to the top of a string of well casing and anchored within a well casing head for fixedly positioning the well casing in the well against well pressures or thermal expansion tending to raise the casing hanger off its seat Within the well casing head.

Another object of this invention is to provide well casing hanger apparatus equipped with anchoring means normally held in a retracted position While the well casing and hanger are being run in the well and seated in the well casing head and adapted to be remotely actuated to set the anchoring means against the casing head.

Still another object of this invention is to provide well casing hanger apparatus which simultaneously sets a packer seal between the casing hanger and the casing head with the setting of the casing hanger anchoring means.

An additional object of this invention is to provide casing hanger anchoring means equipped with apparatus to prevent the premature setting of the casing hanger anchors or of packers adapted for simultaneous setting therewith.

A further object of this invention is to provide casing hanger anchoring means adapted for remotely actuated selective release from the casing head for removal of the casing and easing hanger from the well.

These and other objects of this invention will be understood from the following description taken with reference to the drawing wherein:

FIGURE 1 is a diagrammatic view illustrating a floating drilling barge positioned over a drilling location and an enlarged section of the wellhead assembly showing the casing hanger positioned therein;

FIGURE 2 is a half sectional view of one of the blowout preventers illustrated in FIGURE 1;

FIGURE 3 is a sectional view of the casing hanger in fixed position with the casing head;

FIGURE 4A is an enlarged sectional detail of the easing hanger packing member and anchor slip assembly in the disengaged position;

FIGURE 4B is the same as FIGURE 4A but showing the packing member and anchor slip in the engaged position with the casing head wall; and

FIGURE 5 is a perspective schematic of the casing hanger assembly and an appropriate running tool for setting same.

Referring to FIGURE 1 of the drawings, a drilling barge 1 of any suitable fixed or floating type is illustrated as floating on the surface. of the water 2 and substantially fixedly positioned over a preselected drilling location by being anchored to the ocean floor 3 by anchor lines (not shown) running to anchors sunk in the ocean floor. Equipment of this type may be used when carrying on well drilling, well completion, or well maintenance operations in water varying from to 1500 feet or more. The drilling barge is equipped with a suitable derrick 4 containing fall lines 5 and a hoist 6, as Well as other auxiliary equipment needed during the drilling or servicing of a well. Thus, in this instance the drilling rig is shown as being provided with a traveling block 7 to which is secured a pair of elevators 8 or other suitable means for connecting to the top of a string of pipe 9.

'Cemented to the ocean floor 3 is a surface casing 10 having a casing head 26 secured thereto. A wellhead as sembly comprising drilling bonnets 11 and 12, ram type blowout preventer 13 and an expansible sleeve type blowout preventer 14 is secured to the casing head 26 by threaded fastener means, not shown. The threaded fasteners may be of the type adapted for manipulation by a remotely operated power wrench as disclosed in U.S. Patent No. 3,256,936.

The interior bore of the surface casing and wellhead assembly communicates with the surface by means of a marine conductor pipe 15, the upper end of which is flexibly secured to the drilling barge 1 by, for example, constant tension cable means, not shown. The marine conductor pipe 15 is a large diameter conduit serving as a barrier between the surrounding water 2 and the wellbore through which the pipe string 9 is extended.

Blowout preventers 13 and 14 are adapted for actuation by fluid pressure conducted thereto through hydraulic fluid pressure control lines 16 and 17.

Referring to FIGURE 3, the casing head 26 is provided with a downwardly and inwardly sloping seating surface or shoulder 30. The casing hanger body 31 is a generally cylindrically shaped element having a bore extending t-herethrough at least as great as that of the casing pipe 38 it is intended to suspend. The hanger body 31 is further provided with a seating surface 32 shaped complementary to that of the casing head shoulder 30 for cooperative sealing engagement therewith. To further improve the fluid sealing eifectiveness between the mating surfaces 30 and 32, the casing hanger shoulder 32 may be provided with packing strips 33 set in circumferential grooves extending around the periphery of the shoulder face.

The lower end 32 of the casing hanger body is provided with internal threading 35 to receive the uppermost end of the casing string 38.

Above the shoulder 32, the hanger body 31 is provided with a groove 39 having inwardly sloping sidewalls. Cooperating with the grooves 39 to hold the casing hanger firmly on its seat 30 are locking pins 40. The locking pins 40 threadably pass through the sidewall of the casing head 26 and securely engage the groove 39 with the frustoconically tapered interior end projections 41. The portion of the locking pins 40 that extends outwardly beyond the outer casing head wall surface is provided with tool receiving surfaces such as the hex head shown.

Next above the groove 39 along the axial length of the casing hanger body 31 is an annular step or shoulder 43 which presents an annular face to the upper axial end of the hanger body, said face lying in a plane normal to the hanger body axis. The outer periphery of the annular step 43 is defined by a diameter that is only slightly less than that of the casing head bore 27 above the shoulder 30. The inner periphery of the annular step is delineated by a cylindrical surface 44 of reduced diameter extending upwardly an appropriate distance to be subsequently described from the normal face of said step 43.

Seated firmly against the cylindrical surface 44 and the face of the annular step 43 is a radially expansible packing ring member 45.

Next above the packing ring member 45 is a generally cylindrically shaped slip ring cage 50. The internal diameter of the slip ring cage 50 is dimensioned for a close slip fit over the hanger body cylindrical surface 44. The external diameter of the cage 50 is dimensioned for a loose slip fit through the bore 27 of the casing head. The lower annular face of said cage 50 is preferably normal to the axis of said cage and abuts the upper annular face of the packing ring member 45. If desired, backup rings 46 may be sandwiched between the annular step face 43, the lower annular face of the cage 50 and the lower and upper annular faces of said packing ring member 45, respectively.

The outer peripheral surface of the cage 50 is provided with a plurality of radially spaced, longitudinally extending slots 51, each having a tapering planar surface 52. The particular angle of the taper 52 is relative to the size of certain elements described subsequently that are cooperative with the slots 51. Also provided in the outer periphery of the slip cage 50 are several, three or more, straight sided limit slots 53 having upper and lower abutment surfaces 54 and 55, respectively. Cooperative with each limit slot 53 is a hanger body secured abutment member 56 which may be a fillister head bolt that is secured to, and partially countersunk in, the cylindrical surface 44 of the hanger body 31. The distance between the upper and lower limit slot abutment surfaces 54 and 55 is relative to the fillister head 56 diameter and the compressible volume of the packing ring 45 as illustrated by a comparison of FIGURES 4A and 4B. When the lower surface of fillister head 56 is in abutment with the lower slot surface 55, the packing ring 45 should be fully expanded and free of compressive stress. Alternatively, when the upper surface of the fillister head 56 is in abutment with the upper surface 54, the packing ring member 45 should be approximately fully compressed and in tightly sealing contact with the bore surface 27 of the casing head 26.

Slidably disposed above the tapered surface 52 and laterally aligned within each said slip slot 51 is a wedgeshaped slip 60. The wedge angle of the slips 60 is the same as the taper angle for the slots 51 such that the outer face 61 remains parallel with the casing head bore surface 27 as the inner face of the slip 60 slides along the tapered surface 52 of the slot 51. The outer face 61 of the slips 60 is provided with friction or surface engaging means such as serrations 62 which may be caused to penetrate the casing hanger bore wall 27 and secure the slip 60 thereto. The upper end of the slip 60 is provided with L-shaped extensions 63 having a vertically leg 64 and an inwardly, radially extending base 65. The vertical leg 64 of the extension 63 may be set approximately flush with the outer face of the slip 60 and secured thereto by any appropriate means such as a screw 66.

At an appropriate distance above the slip cage 50, considering the stroke length necessary to compress the packing member 45, the radial difference between the cylindrical surfaces 44 and 27 and the taper angle of the surface 52, the hanger body 31 is provided with right-hand male threading 67 on the upper end thereof to receive a cylindrically shaped packing gland member 70. The lower, inner cylindrical surface of the packing gland 70 is also provided with treads to mate with the hanger body treads 67. The lower, outer cylindrical surface of the packing gland 70 is provided with a circumferentially extending groove 71 having upper and lower abutment surfaces to snugly receive the base member 65 of the slip extension 63. Slip rings 73 may be sandwiched between the lower abutting face 72 of the gland 7t) and the upper abutment face 68 of the slips 60. The upper cylindrical end of the gland 70 is provided with running tool receiving surfaces such as radial slots 74 that are adapted to receive means such as lugs 75 that project from the lower end of running tool 76 as shown in FIG- URE 5. The running tool 76 is adapted to be secured to the lower end of the pipe string 9 by which it is lowered through the well bore into engagement with the gland 70. The lugs 75 serve to couple the tool 76 and the pipe string rotatively with the gland 70 so that rotation of the pipe string 9 from the surface in either direction turns the gland 70 on the threads 67.

To secure the slip cage 50 and slips 60 together for controlled relative axial movement, a yieldable pin 80 extends between the two members normally across the face of inclined surface 52. The yieldable pin 80 may be formed from a malleable metal screw having a reduced shank portion of a size relative to the cantilever bending load imposed on the head 81 by the slip 60. The threaded end of the pin 80 is secured to the slip cage 50 in the bottom end of a counterbore 82. The head 81 is slidingly disposed in a slip penetrating borehole 83. When the slip 60, the cage 50 and the pin 80 are in assembly, a substantial annular space between bore walls on the pin shank remains.

Around the upper internal periphery of the casing hanger body 31, threads are provided on a tapered run to receive an internally concentric seating member 84. The seating member 84 is of a generally hollow cylindrical configuration having a frustoconically tapered seating surface 85 at the upper end thereof. Seating surface 85 serves the same function as the seating surface 32 on the casing head wall 26 for a second string of production tubing, not shown, to be sealing secured in position internally concentric of the string 38.

Internally, the seating member 84 is provided with left-hand threads 86 to receive a similarly threaded hanger nut 87. The length and gage of the threads 86 and nut 87 is dimensioned to support the entire casing string 38 and is the connective means by which the string is lowered into the well.

The hanger nut 87 is provided with a through bore having a polygonal internal periphery to slidably receive a similarly shaped mandrel 89. Mandrel 89 is secured to the tool 76 or vice versa in some conventional manner which may be as illustrated in FIGURE 5. The lower end of the mandrel 89 is provided with a sub or shoulder 90 which limits the axial movement of the hanger nut 87 and supports the weight of the casing string 38 on the pipe string 9. The axial dimension between the lower tip of the lugs 75 and the upper face of shoulder 90 must be adequate to allow the tool lugs 75 to engage the slots 74 while the sealing surface of the casing hanger body 31 simultaneously engages the casing head sealing surface 32 when the hanger nut 87 is in full thread engagement with the sealing member 84. Preferably, the axial length of the mandrel 89 should be slightly greater than the minimum length described to allow the pipe string 9 to rotate the hanger nut 87 via the mandrel 89 into full engagement without turning the packing gland 70. Additional-1y, there should be sufficient clearance for the hanger nut 87 to ride axially up on the mandrel 89 to a position of complete thread disengagement with the sealing member 84 when the lugs 75 of tool 76 have turned the packing gland 70 down to the full axially compressed position shown in FIGURE 4B.

Operation At the surface, the upper end of the upper section of casing 38 is provided with the casing hanger assembly heretofore described with the packing member 45, the slip cage 50, the slips 60 and the packing gland 70 in the expanded condition illustrated by FIGURE 4A. The sealing member 84 is secured to the casing hanger body 31 in the manner shown in FIGURE 3 and the casing string and hanger assembly is secured to the pipe string 9 via the hanger nut 87 and mandrel 89. The assembly, supported by the pipe string 9, is lowered into the well until the hanger body 31 engages the seating surface 32. On the way down through the conductor pipe 15, it will be necessary for the casing hanger assembly to pass through the expansible sleeve blowout preventer 14 such as a K type manufactured by the Regan Forge and Engineering Company of San Pedro, Calif, illustrated in FIGURE 2 and having a fluid pressure actuated, pipeconstricting, expansible sleeve member 18, which, when pressurized by fluid in the pressure annulus 19 from the hydraulic control line 17, constricts around the outer surface of a pipe string 9 extending therethrough to block the well bore annulus. Although the operating pressure on the blowout preventer will be relieved at the surface during the casing running operation, there will still be a static head of pressure on the expansible sleeve 18 due to the head of pressure fluid remaining in the control line 17 above the packer. Since the blowout preventer 14 may be physically located at, for example, a depth of 300 feet below the surface, the residual pressure head thereon will be proportional to said depth. Hence, the constricting effect of the blowout preventer sleeve 18 will never be completely relieved .and the casing and the hanger will necessarily need to be forced through the constricted opening of the packer. The effect of forcing the casing hanger past the blowout preventer packer would, Without the axial displacement limiting function of the abutment fillister 56 cooperating with the lower abutment surface 55 of the limit slots 53, be to slide the slip cage 50 up on the casing hanger body cylindrical surface 44, thereby wedging the slips 60 out against the inner wall of the marine conductor pipe into premature setting engagement.

Once the casing hanger body 31 is seated on the surface 32 the locking pins 40 are turned into engagement with the hanger body groove 39 to force the seat 32 down into uniform, sealing contact with the sealing face of the shoulder 30. The locking pins 40 may be turned into locking position by a remotely operated power wrench, not illustrated, but of the type disclosed in US. Patent No. 3,256,936.

When seated and secured, the pipe string 9 is further lowered to allow the lugs 75 to engage the tool slots 74. Pipe string 9 is then turned in right-hand rotation by the drilling rotary table, not shown, to effect a simultaneous turning of both the packing gland 70 and the hanger nut 87. The result of such turning is to axially advance the packing gland 70 on right-hand threads 67 and simultaneously disengage the hanger nut 87 from the hanger by axially withdrawing it from left-hand threads 86 and allowing the nut 87 to slide axially up the length of the mandrel 89. When the hanger nut 87 clears the threads 86, the casing string 38 and hanger are axially free of the pipe string 9 and the entire weight thereof is supported on the seating surface 32.

As the gland 70 is advanced on the lead of the hanger body threads 67, a downwardly directed force is transmitted from the upper abutment surface of the groove 71 and the lower abutting face 72 to the base 65 of the slip extensions 63 and the upper abutment face 68 of the slips 60, respectively. Since the malleable pin is sized to resist yielding until the compressible packing member 45 is set, these forces are transmitted across the tapered surface 52 to the slip cage, thereby sliding it downward along the cylindrical surface 44 of the hanger body 31 to compress the packing member 45 against the upper face of the step shoulder 43. The resulting volumetric reduction between the backup rings 46 causes the packing ring material 45 to flow into fluid-tight sealing engagement between the hanger body 31 and cylindrical surface 27 of the casing head 26.

Since the length of the limit slot 53 is proportioned to allow only an adequate, predetermined maximum allowable volumetric displacement of the packing ring member 45, the axial displacement of the slip cage is positively stopped when the upper surface 54 of said slot 53 engages the upper surface of the fillister head 56. Continued advancement of the gland 70 on the hanger body threads 67 transmits sufiicient force to the slips 60 to bend the malleable pin 80, thereby allowing the slips 60 to slide downwardly and outwardly along the tapered slot surface 52 into engagement with the casing head cylindrical surface 27. Suflicient force on the slips 60 will cause the serrations 62 to penetrate the surface 27, thereby setting the slips 60 as an additional surety against the casing hanger body 31 from being lifted off its seat on the casing head shoulder 30 by any fluid pressure which may accumulate in the well bore annulus around the outer surface of the casing string 38.

It sometimes becomes necessary in well operations to remove the casing string 38 after it has been set. In the case of some prior art casing hangers it is necessary to cut the casing hanger out with a milling bit, allowing the released casing to drop to the bottom of the hole to be later retrieved with a fishing tool. In the case of the present invention, however, such milling and fishing operations are made unnecessary by simply returning the pipe string attached tool 76 and mandred 89 supported hanger nut 87 to the position shown in FIGURE 3. Lightly torqued left-hand rotation of the pipe string 9 will turn the hanger nut 87 into full thread engagement with the seating member 84. At the same time, lugs 75 on tool 76 will turn the packing gland 70 on right-hand threads 67 to pick up on the bottom abutment surface of the slip extension base 65. The result is to draw the slips 60 away from the casing head wall 27 and simultaneously relieve the packing ring member from sealing engagement with casing head wall 27. With the slips 60 retracted, the locking pins 40 withdrawn and the hanger nut 87 engaged with the sealing member 84, the casing string 38 and hanger are ready to be picked up by the pipe string 9 and withdrawn from the well bore to the surface.

We claim as our invention:

1. Casing hanger apparatus for hanging a string of casing in a well from a casing head positioned at the head of the well and having an annular seating shoulder therein, said casing hanger comprising: a body member having a bore therethrough and adapted to be secured to the top of a well casing; a downwardly and inwardly sloping seat formed on the outer surface of said body member for mating engagement with said annular seating shoulder in said casing head; said body member having a reduceddiameter portion above said seat forming recessed shoulder means; an annular compressible packing member disposed around said body member with a lower surface operatively abutting said shoulder means; slip cage means axially slidably disposed around said body member with the lower end bearing on the upper surface of said packing member, said slip cage means having an upwardly, inwardly tapering longitudinal outer slip surface; slip means longitudinally slidably disposed on said slip surface whereby said cage means and said slip means operatively cooperate to form radially expansible wedge means between said body member and said casing head, said slip means having contact faces of a form to prevent upward movement of said body member relative to said casing head; yieldable means disposed between said slip means and said cage means to longitudinally secure one relative to the other; and actuating means carried by said body member and adapted to engage said slip means whereby initial movement of said actuating means in one direction longitudinally displaces said slip means and cage means together to compress said packing member into fluid sealing engagement between said body member and said casing head and further movement of said actuating means overcomes said yieldable means to slide said slip means into engagement with said casing head.

2. Apparatus as described in claim 1 wherein said actuating means has circumferential slot means around the periphery thereof and said slip means has L-shaped extension means on the upper end thereof, the base of said L-shaped extension means in mating engagement with said circumferential slot means whereby adjustment of said actuating means in the other longitudinal direction releases said slip means contact faces from locking engagement with said casing head and withdraws said slip cage means from compressive engagement with said packing member.

3. Apparatus as described in claim 1 wherein said yieldable means is a malleable pin, said Pin havingone end secured to one of said wedge members in the bottom of a first bore, the effective diameter of said first bore being substantially greater than the effective diameter of said pin, the other end of said pin terminating with an enlarged head, said head being slidably disposed in a second bore in the other of said wedge members, the effective diameters of said head and said second bore being substantially equal.

4. Apparatus as described in claim 1 wherein said slip cage means has longitudinal slot means in the inner wall thereof and abutment means secured to said body member extending radially outward therefrom into engagement with said longitudinal slot means whereby said cage means is allowed only limited longitudinal sliding displacement along said body member.

5. Apparatus as described by claim 1 wherein said actuating means is threadably secured to said body member, said actuating means having radially extending tool slot means in the upper end thereof, said tool slot means adapted to receive lug means protruding from the bottom end of running tool means, said running tool means adapted to be secured to the end of a pipe string whereby said actuating means is longitudinally adjusted on said body member by mating said running tool lug means with said tool slot means and rotating said pipe string.

6. Apparatus as described in claim 1 wherein said body member has circumferential groove means around the outer periphery thereof between said sloping seat and said recessed shoulder means, said circumferential groove means having inwardly tapering sides, radially extending locking pin means threadably received through the wall of said casing head, said locking pin means having frustoconically shaped interior ends adapted to engage said tapered sides of said circumferential groove means, the exterior end of said locking pin means protruding beyond the outer wall surface of said casing head and having tool receiving surfaces thereon whereby said body member seat may be pressed into sealing engagement with said annular seating shoulder and held in place by turning said locking pin means into engagement with said tapered sides of said circumferential groove means.

7. Apparatus as described by claim 1 wherein said actuating means is secured to said body member by righthand thread means, said body member having left-hand thread means along the bore thereof and running tool means adapted to be secured to a rotatable pipe string, said running tool means being adapted to engage said actuating means and said left-hand thread means whereby right-hnd rotation of said running tool means simultaneously operates said actuating means to set said slip means and compress said packing member and disengage said running tool means from said left-hand thread means to axially release said hanger apparatus from said running tool means.

8. Apparatus as described by claim 7 wherein said running tool means comprises axially elongated mandrel means having polygonal sides and hanger nut means axially slidably disposed around said mandrel means, said nut means having left-hand thread means on the outer peripheral surface thereof adapted to engage said lefthand thread means of said body member and bore means extending axially through said nut means, said bore means having polygonal side surfaces whereby rotational torque may be transmitted from said mandrel means to said nut means.

9. Apparatus as described by claim 8 wherein said mandrel means has abutment means on the lower end thereof, said abutment means limiting the axially slidable movement of said nut means relative thereto and adapted to support said hanger apparatus and a casing string secured thereto.

References Cited UNITED STATES PATENTS 2,173,351 9/1939 Bradshaw 166124 X 2,230,447 2/1941 Bassinger 166-124 X 2,313,169 3/1943 Penick et al. 285-433 3,083,770 4/1963 Villalon et al. 166-124 3,241,616 3/1966 COX l66124 X CHARLES E. OCONNELL, Primary Examiner.

RICHARD E. FAVREAU, Assistant Examiner.

U.S. c1. X.R. 285-143 

